I personally think 2 from same packet breaking could be a bad batch. A lot of people don't trust ebay sellers and would assume, like me, that Boots being a well know store would be one of the most reliable places. Well I've been buying from the same seller from ebay for about a year and had no accidents whereas a few years ago I bought some exs condoms from ebay. different seller, and 2 broke in succession like you so it's not that ebay as a site is good or bad, down to the sellers of course.
I never contacted the seller about the bad ones as they might just say I didn't use them properly. The same probably if you let Boots know but they would probably need lots more complaints to investigate anyway (that's if anyone wasn't too embarrassed to contact them)

. One break I tend to think not enough lube or something but 2 in a row sounds dodgy.