Continental GT air strut rebuild advice.

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Hi folks, I've replace the front Air Struts with some RMT rebuilt ones and so far they seem great, the car feels much better than it has ever done since I've owned it which is around around 5 years. I also have a much slower leak on the rear but RMT can only rebuild rears sent in and as I'm in the UK I don't really want the car off the road for the time it would take to send them to the US, get them rebuilt and returned. So I'm looking at getting a pair of the Aerosus Air Spring bags and replacing them my self, so now to the questions.
Has anyone any experience of replacing the air springs on the rear shock?
Any special tools needed, is it a hard job or pretty straight forward?
By the air springs I do mean just the air springs not the whole shock, so removing the air spring from the damper and fitting the Aerosus replacement air springs.
Does anyone know of anyone in the UK who will rebuild the struts?