I know it is stressful Maureen, but try not to get too worked up. You need a clear head to make the right decisions, and whatever happens, it’s never worth jeopardising your health over it.
I hope one of the lawyers who participate here will correct me if I’m wrong, but I expect that a new guarantee won’t make any difference in principle, as it shouldn’t imply any change to the original contract being guaranteed. But this is the sort of thing you really need to check with your solicitor, who will probably need to see the details of the guarantee. Do you have a good, independent solicitor in Spain? And have you or your solicitor spoken directly to the financial company issuing the guarantee?