corfu data roaming costs

You might have connected to a mobile network in Albania @Macey1965.
Where you staying/visiting the NE end of Corfu?

Did you use your handset on a ferry while in Greece? 
Roaming at sea sometimes uses the vessel’s satellite based mobile network, which is expensive and not included in your plan allowances. 
 

Didn’t go on a ferry stayed in the north of the island in Sidari shocked it would pick up the mast in Albania however that may be the reason. I thought so myself, thanks for your reply.

Hey @Macey1965, one way to avoid any out-of-plan use, while roaming, is set your iD account bill cap to £0. 

Hi @Macey1965 

Does the charge mark itself as something different on the bill?

If connected to a neighboring countries’ mast which is a chargeable area, this would charge, we’d recommend using manual network selection as opposed to automatic and setting the bill cap to a comfortable amount.

Tom