Nokia 5530 query

[Stephface]

Hello, I am new to this forum and would appreciate any advice.
I bought a nokia 5530 recently from an online buy and sell advertisement. It was quite cheap so I should have anticipated problems. I have tried contacting the seller but have had no luck.
The problem is that there is a security lock present on the phone. I have tried to research a solution but have found none yet.
I am wondering if there is anything I can do myself to unblock the phone? Or would a shop that offers unblocking be able to help? (I think that generally refers to network unblocking)
Please help if you can!
Thanks