rns315 overheating

[bicks]

Hi My 2013 b7 tsi has the 315 unit fitted, works fine for about 40 miles then switches off sat nav, phone,cd etc and after about 20 seconds comes back on and have to start again with settings and will then switch on and off every few minutes untill i switch it off myself and leave it to cool down for 20 miles or so and then the sequence starts again
if it was just one thing not working i could cope with it but as it is its bl---y frustrating . any help would be greatly appreciated .