If you buy that pet from him, why would he care for it or any other pets in the future. He is gonna make a profit selling sick animals.
Your only option is to go and see the manager, tell him the snake is gonna die and ask him if he can give it to you for free.
he'll probably say no, but there is nothing more you can do, and nothing more you should do.
I did a stupid move like this once, and my animal died 2 months later. then I felt bad for having a dead animal even though it wasn't my falut at all and I lost some $$ also.
Don't encourage petshops like that.
Cornsnakes / JCP / Sinaloan Milk / BRB / Veiled / ATB / WLP / Crested Geckos / Uroplatus Henkeli / Vietnamese Cave gecko / Chinese Cave gecko *What's Available*