I've used ATS before for this a few years back, no problems they even gave the car the once over and no issues found (and it's quite an old car) so no upselling.
Would do this again except went for the Groupon Mr Clutch deal from a few weeks ago.
Hope some find this useful.
Now for the blurp...
Car air-con recharge service is £28.95
Car air-con recharge service and an anti-bacterial treatment £32.95
Car air-con systems can be refreshed with this one-hour recharge and optional anti-bacterial cleaning treatment
Technicians will perform a pressure test to detect leaks in the air-con system; if none are detected, the service will go ahead and the air-con system will be recharged, meaning that drivers can stay cool when out on the road.
The Fine Print
Expires 2 Aug 2017. Limit 1 per person, may buy 1 addtional as gift. Booking required by phone, please find contact details online via http://www.atseuromaster.co.uk/centres/centre-locator?type=air_con.
Present printed Groupon voucher on arrival. 24-hour cancellation policy. Voucher cannot be used with online bookings on the ATS Euromaster website. Excludes electric and hybrid vehicles. Not valid for system repairs. Air Con Services not available at every ATS Euromaster Centre. Valid for various locations Mon-Sat. Applies to vehicles with R134A refrigerant gas only. Vehicles with R1234YF refrigerant gas are excluded. For details of the refrigerant gas used in your vehicle refer to your vehicle manufacturer handbook. Groupon is the seller of voucher, but ATS Euromaster are responsible for fulfilling all services included in the offer. Cannot be used in conjunction with any other offer. Full terms and conditions for both offers can be found at http://www.atseuromaster.co.uk/special-offers/groupon-terms-conditions.
Verified using our merchant’s website on 8 May 2016.