Ok guys, on Monday I did the online purchase I was going for (since I have a higher limit). Tuesday morning I received an email saying that some problem with the payment arised and the store had to cancel my order:
"I am very sorry but unfortunately there appears to have been a flag raised on the payment and under the advice of our card company, I have cancelled the order."
I asked for details and what I got was this answer:
"Unfortunately, we are not told the exact reasons for the payment not being accepted and are advised to cancel the order."
I don't know why I had a flag, I don't know if they can see that wirex is behind, but banks in the UK do have a history of making things hardes for bitcoin users. On the other hand, I've bought other stuff with my previous wirex card (not that much expensive though).

Fortunately, the store crew is very helpful, so I'm arranging a another way to pay for it.

Right now I'm waiting for the refund to arrive (the store said they already send the refund...let's sit, wait and hope).