Spanish Bank Account

I am dealing with an estate with a Spanish Bank account held in the joint names of the deceased and his wife.
The bank have frozen the deceased’s half share of the account and will only allow the surviving spouse to access her half share of the account.
To release the deceased’s share the bank have asked for a Last Will and Testament Certificate issued by Spain’s Registro General de Actos de Ultima voluntad and also the document fulfilling the same function issued in the deceased’s country of origin (uk) - this means nothing to me! They are also asking for the Original Will.
My own research suggests that a foreign will is valid and enforceable in Spain but it must be translated into Spanish and be legalised before a Spanish Consul or affixed with an apostille. Grants of Probate must also be translated and legalised or affixed with an apostille.
Has anyone come across this situation and is able to clarify what the bank should accept? The account is not worth a great deal so we don’t want to incur unnecessarily high costs.