I paid £250 for a breaking bad signed dvd by Bryan Cranston

Here it is with the certificate:

https://ibb.co/GCSYwH1

I got a 2nd opiniok on Reddit  and an autograph dealer told me things look off so I got a 2nd opinion from Beckett £10 quick opinion and I got a reply  saying ‘unlikely to pass authentication’

Then I read that’s hot or miss and people have sent them genuine signed and theyv still said the same

So i sent it to an AFTAL approved group here in the U.K. and he emailed me back and said ‘in my opinion it’s not genuine’

The seller on eBay had it for £300 or best offer

I offered £250 and he accepted

He said he bought it off a collector and should i return it for a refund?