Hello @AllyJay
What a bad time you are having.
It is definitely worth sending a letter with the photos attached but they may say you could have gone around the drains and that there is an element of negligence on your part.
As @Zoffiel says, you need to be clear what your expectations are - and remember that you will be fighting a giant so is it worth the stress and time to you ?
Perhaps you need to let them know of your issue so you feel you've done something about it for others.
Good luck if you go ahead and please keep us informed.
Summer :)