Why are Scottish Power topping up my smart meters?

Joined Scottish Power a few weeks ago. I found I have £30 in both my electric and gas meters. That’s £60 given to me for free.

A few days ago they topped up my gas meter again back up £30.

Why are they doing this? It’s scaring me because I think I’ll need to give them the money back.

I’m thinking of moving back to OVO.