A child of a reader called Elaine was diagnosed with coeliac disease in 2009 and is on a gluten-free diet for life.

“What followed was a steep learning curve for the whole family in tracking which foods were suitable for our child’s needs,” she writes. “We cook a lot at home so the major change was to find gluten-free substitutes for the foods we eat regularly.”

Not all gluten-free substitutes are palatable, however. “One of these is flour, which we tend to use a lot of in our house, going through a 1kg pack every 10 days or so. We use it for pancakes which is a breakfast staple in our house, for baking, sauces and so on. So once we found a substitute we liked, we stuck with it.”

She is referring to Doves Farm Gluten Free Self-Raising flour, which is available in most major retailers a lot of the time and in some local shops.

"The difficulty I have is that recently I have had difficulty sourcing the product at a reasonable price. When I first began to purchase the flour at Tesco, it was less than €2 per bag. It is now retailing at €2.49 when available. I have queried this with them a few times, but all I have heard back relates to inflation and the global increase in grain prices."

She says the price ranges from about €2.05 in supermarkets to as much as €3.79 in a local shop, an “extraordinary” difference of almost 90 per cent”.

Last week she found Supervalu selling the flour for €2.05, compared with €2.49 in Tesco and €3.79 in her local shop.

“While I realise that the major supermarkets have the power of bulk-buying and I end up paying a premium for the convenience of a local shop, this level of difference is bizarre.”

She says the smart move is to buy a few bags at a time, but she does not have much storage space. “I am not complaining about the price, but the differential in the price at the various retail outlets.”

It is not unusual for things to cost more in a local shop than in a large supermarket. Generally speaking, such shops have significantly higher overheads. They cannot buy in bulk, as shoppers spend significantly less there than in large supermarkets. But an increase of almost 90 per cent seems wildly excessive. Studies in the UK would suggest price differentials of 15-40 per cent are more common.

A fight to get an iPad fixed

A reader called Anthony bought an iPad Air 2 in December 2014 in PC World in Jervis Street shopping centre, Dublin. Last January the screen flickered, then faded and eventually stopped responding. "It had been working perfectly up to then, and hadn't been dropped or had any damage. I did a reset, and when it came back on the touchscreen didn't work. I then did a software update through my laptop, and when that didn't yield any results I did a full reset through the iPad. Again nothing," he writes.

So he spoke to Apple. "They said nothing could be done because the device was out of warranty and said I needed to go to PC World. I went in to Jervis and asked for the manager. I explained my problem and he said there was nothing he could do, that under EU law, once it was out of warranty, it wasn't their responsibility and I'd have to pay a fee for a repair.

“When I asked what the fee would be, he said he didn’t know and he wasn’t the person I should have been talking to. He then walked away.”

Anthony says that when he spoke to the “engineer”, he was told he could not repair iPads “and my only option is to find another repair shop and there was nothing they could do. It was out of warranty.

“I said that there was an expectation that after 13 months the device should still work, but again he just said there was nothing he could do. I’d like to point out I was more than pleasant throughout. Because I was hitting a wall, I knew there was no point in pushing any further as nobody was interested in helping.”

We contacted PC World and a spokeswoman accepted that all was not as it should have been. Our reader’s iPad is in the process of being repaired.