When will I ever learn 😳

Jessica
Puppy-Sitting Rant!
When will I ever learn to say "no" or "how much are you going to pay?" when my mum asks me to pup-sit! 
My SO and I have a chihuahua.  My mum and step-dad, who live 1.5hours away, also have a chihuahua.  We take care of their chihuahua once in a while when they go away or whatever.  He's house trained... but only in my mums house and she doesn't believe me.  He comes here and cocks his little leg up and pees on almost everything!  It's not like I don't let them out often enough, I leave the door open and they can go outside whenever.  I know he's probably just trying to mark his territory or whatever but peeing on the remote... Really?!?   
Oh and, my bed space when mums dog is here goes from me having 1/3 of the bed to playing twister with 2 chihuahuas and an SO who sleeps like a log but also flails and hogs the bed! Â