Mattress worse after exchange Bradlows and Sealy

I bought a Sealy bed in 2017 at Bradlows Festival Mall. I noticed a tear about a year later and informed them. They came to collect the mattress and exchanged it in 2018 but now I'm starting to notice some lumps on the mattress. The mattress is worse than the one I had before.

I'm not happy about this service and don't understand why I was given something that's not of good quality that I had paid for.