Keep or sell?

[Ed-B-Spurs]

I wanted to get peoples opinion, currently in my 3rd season as Aston Villa in the premier league. Finished 9th in my first season back and tried to build a squad this transfer window round.

I have just had a non negotiable bid come in for Denis Vavro (CB) for £26.5million. Bought him for £2.8million 18 months ago and is valued at £12million. He averaged 6.96 last season playing virtually every game. Question is would you accept or decline? 

I currently have Maresic, Markovic, Chester, Dann and Okore as centre backs 

Thanks