Bug found in chees

I recently brought cream cheese from my usual store (name removed). I found a grub or a part of a worm embedded after I consumed some of the product. This caused me to vomit violently and I am unable to eat cream cheese at all. I contacted the shop (name removed) who said they would investigate it. They recently wrote offering me double the refund plus a good will voucher for £5 I am not in the least out to make money, but I feel as though they have not taken this seriously enough. I feel this gesture was inadequate. What do others think? Vicky