Pets At Home

I have had with one of your tinned dog foods.
Both of my dogs have become severely unwell after eating it, with diarrhoea and mucus throughout the house. I have never seen them react like this to any food before. At first I was unsure what was causing it, so over the past couple of weeks I tried giving the food on and off to confirm whether it was related.Each time they had the tinned food, the diarrhoea returned.
I am now confident that the issue is linked to the food itself. I have only used two tins from the pack and would like to ask whether it would be possible to return the remaining tins for a refund or exchange.
Unfortunately I no longer have the receipt, however I am a Pets at Home member and I did use my membership card when purchasing the item. I also have the transaction showing on my bank statement if needed.
Please let me know what information you need from me, such as batch numbers or purchase details. It is so difficult to find an email that works.

Frankly, they could be better, if they tried much harder.
Their weak point is their customer service, of course. I can't say anything negative about stores, products, and quality.
I ordered an item for my cat and it wasn't delivered on time. So I called their customer support and asked hat happened. They said that the item was on back order and offered me an alternative. I refused. They said I have to wait for too long and I shouldn't reject what they offer. But I did it again. Because I ordered a certain item for reasons. Probably, my answers made her angry and she said: oh well, not going to beg you, sit and wait forever. And then she hung up.
So customers treatment leaves much to be desired.