I also agree with many comments above.
Please also consider the cost of switching companies.
It will be unlikely you will be able to transfer the monitoring so you will have the cost of new kit and connection charges.
Also other companies maybe cheaper but make sure you consider what's included.
Parts, servicing, call outs, out of hours are they extra or included. Will the new signalling be to the same Grade as the out going.
I think for Redcare GSM it sounds about right depending on location?