Terrible customer service

I purchased ram as the lockdown started and when installed it I found that the ram was incompatible with my laptop. As the shop was about to close I called the store and asked for assistance. I was told to come after the lockdown. I only noticed that the store was open last week on the 13th of June 2020. I came to the store today on the 20th of June 2020 and they refused to give credit for the ram telling me that I took too long to come in store. Now I have a product I can’t use and they are offering me a minor discount on my current purchase. If I didn’t need the current hard drive purchase I would have just left the store.