Mortgage Rates and Euribor don't seem to tie up

Hello,
       I have the Polaris/CAM mortgage. My understanding is this is based on 6 months Euribor + 1.1%, this would be reviewed annually after 18 months and they use the Bank of Spain Euribor rate from two months previous. BoS refers to http://www.euribor-rates.eu/euribor-rate-6-months.asp

I was surprised to notice this has changed recently and although not much it made me review earlier rates which appear higher than expected. Even though it may just be 0.25-0.3% out, I'm keen to get this fully understood.

I contacted CAM via eChat and no luck was referred to a branch. Before I go down the email the branch route and to check my understanding does this lot below make sense.

                                        Review  Date            Mort Rate   Expected Euribor  Actual Euribor (2m prior)
Initial                               20/08/2008                 6,10%        5,1%                      5.126              
18 month                         28/02/2009                 4,50%        3,4%                      3.03
Annual                             01/03/2010                2,34%        1,24%                    0.99
why not annual?              02/08/2010                2,35%        1,25%                    0.99

 Anyone noticed something similar or have an explaination?

I believe they are based on the 3 month Euribor rate, rather than the 6 month Euribor rate.

I have the same deal with CAM, 1.1% over. I completed in June 2008 and my first review was Decelmber 2009. They used the October 2009 3 month Euribor (1.243%) Plus 1.1, giving me a payrate of 2.343%

This ties in with the rates on this web site (use the last Column) http://www.bde.es/clientebanca/tipo/referencia/temas/tipos.htm

Think reviews are annually after your first review, so I will be looking closely at next months Eurobor rate, as they will enable me to calculate next years payments.

Just for an update CAM have stated the mortgage is based on Euribor 1year, using 1 month average taken 2 months before the required date. The reason for the recent change is as a result of moving from I/O to repayment so recalc'd as new event. 

This ties up closer with my figures and maybe makes sense if the mortgage is reviewed annually.