Assuming you have the newer (since December 2017) purple sim, you can reset roaming without having to log on to your account.
Press plan, then controls and you'll find the roaming switch.
Annoying that movistar and voda es have the whole thing, but 2 on one and one on the other.
You could try switching roaming off for some hours, but then you might lose all service. Then switch it back on again, wait a while, restart the mobile and cross fingers that it gets to your networks and works.
You'd have thought the message you got would be Spanish rather than French though.
Thanks - I've got a purple SIM, and the virgin app - my plan is indeed set up for roaming. I have half a suspicion I may have barred international calls at some point, but can't access my virgin mobile account on the web from here (presumably it's restricted to UK IP addresses?)
Don't really want to turn it off as I'll have no way to turn it on again!