I have an account at Banco Santander in Spain and they messed up a transaction so they owed me a refund. They insisted on giving me the refund in Banco Santander shares! They own so much property here as the developers have gone bust and nobody knows what property is worth as it is not trading.
I believe that you were using Santander to do a certain deal and, unless we know all the details, you are frightening us.
If you have a bank account with Santander I would say that your money is safe, Up until now, at least.