Nice posting Yvonne. I'd say the problem with the OP's "topsoil" is the compost. Who knows where they got the compost, or what is in it. Probably no perlite, but could be lots of other non-tort friendly things; plant friendly yes, tortoise no.
All the products Yvonne listed are good, so Thadus look for one of those, vice the unknown "topsoil". When our sully was small, we used coco coir, now we use cyprus mulch in his house.
I also use potting soil.
I'm sure it differs by location, but here in Florida the top soil has a lot af sand in it.
I have orchid bark covered by a layer of bark and potting soil mixed.
It's about two bucks a bag.