I'm with M&S too, I think my renewal is due in July or August, so it is interesting to see how yours has gone up.
We have no excess and at the moment pay £10 something for one Newf, £11 something for the other one and yet we pay £17 something for Tia, which I have never thought makes sense as there is supposed to be 10% off what we pay for her anyway!
I don't think we have made a claim for any of the dogs in the last year, so if they put the price up too much I won't bother paying it, I shall just put £50 into an account every month just in case someone gives me a big bill