SSD from Bookyard keeps crashing

I have an old MacBook where I lost the original SSD when I used a third party one. I now ordered a (presumably refurbished) SSD from the Bookyard advertised as compatible for the same make but 500GB instead of 256. Upon installing it, the machine worked fine for about 5 minutes before shutting down without warning and also without any report upon rebooting successfully. This was repeated a few times, until I gave up. The shutdown happened sometimes less than a minute after booting, sometimes a few minutes later, maybe up to 5 or 6.

I assume that the Bookyard sent me a faulty SSD and I will contact them about it in the morning in the hope that they will replace it.

Is there something in general that I need to know about replacing SSDs for the MacBook? Is it a straightforward process or am I likely to have to say goodbye to my old machine? Does Mac replace hard disks for older models and what do they charge for it?