Hi Michael.
The new rate seems there or thereabouts although, like you, it seems that rate should be closer to 4% rather than that extra 4.5%! Have you asked them to give you the basis of the new rate; you may get a reduction if you can show otherwise.
Each bank has it's own method of calculating the reset rate; CAM's is certainly one of the kinder in this market.
And, no, whilst most use Euribor, several use an index abbreviated as IRPH. There are various such index but the Caja is that used by most. This index takes the average rate over a much longer period, supposedly to flatten that trend line but, unfortuantely, due to the speed and extent of the ECB Base Rate reductions, those borrowers on this index are being heavily 'penalised' at present. In fact, as the Euribor based average 'pay rate' now should be closer to 4% (and lower for new business) and the IRPH at least 5.5%, it may even be worthwhile for borrowers on IRPH to consider asking their lender for a switch to Euribor! This will come at a cost so that has to be taken into consideration against the interest rate gain.