Can anyone  recommend  suitable garage. 

Morning Kevan

Welcome to the Forum 

The battery in the telematics unit is/should be rechargeable so the fault may lay elsewhere but the battery is easy to replace if needed 

If you have a little patience and ability at DIY you can change it yourself the only bit you may need help with is re-setting the Fault code 

First use www.realoem.com put the last 7 digits of your Vin into the search box, it will bring up your model. Look in the communication section to get part numbers and the location of the Telematics unit. Removing the unit will need a little patience a very clean hands, The battery is under a cover on the Telematics unit

Before starting disconnect the cars battery (Neg first) When yu have changed the battery in the Telematic unit and put it back reconnect the cars battery. it should with luck reset any codes. If not this is the point where you need either a Garage or  member near you who has a BMW capable diagnostic programme to reset the Fault code

If you really need a Garage Google the Register of BMW Specialists there should be one near you

Good Luck

Dave