Hi, my name is Paul and I will try to assist you.
in around 90% of telephone problems we see it is the phone causing problems rather than the car - in the first instance switch the iphone completely off & restart the phone to see if this then works in your car
if not then delete the bluetooth connection from both the iphone & the car (unless you have full phone prep with a bluetooth adapter or iphone cradle - in this case just delete it from the iphone). Then try pairing the phone again with a fresh connection.
If the phone still does not connect after this then I would try getting hold of another phone to see if this works - it may be a physical problem with your phone if another phone pairs ok
If after all of this the phone will still not connect then it will need to be checked out on Mercedes STAR diagnostic tool to see if there are any faults in the system or if there is a software update for the car.
Best regards, Paul
thanks . I am certain it is not my phone as it's the same with my son;
's phone and my husband's but I will see what happens when I delete and restart the bluetooth connection in the car.