Hii I went to resize...

Hii I went to resize my rings my late mother in-law gave to me before she died last year March ...it was not damaged in very good condition Judy needed to be resized my fingers are smaller then hers they charged me R830 for all....and twice I went back asking why my rings are now suddenly going black after a few days ...so they gave me a cloth to rub and it does disappear after rubbing my issue is why I need to keep doing that when the clearly damaged it ....so what arey options to resolve this .