does anyone know if phone masts can disrupt electrical systems on your truck i took over a 64 plate merc on Monday everyday I trundle along the A419 Swindon, south is not a problem,coming back north there are two masts on the left just after the blunsdon turn off,i by that time am on cruise control,without fail just as I pass the masts the cruise control cuts out ,allways at that particular spot,seconds later I can put it back on,i thought maybe I am touching something,but no I keep my hands at the side of the steering wheel and sure enough it cuts itself off ,very weird is all I can think
There’s something called RFI (radio frequency interference), aka EMI (electromagnetic interference) which is when radio transmissions can affect other electronics. There is evidence that cruise control systems can be affected, worryingly some cause major acceleration, but it could easily cause the system to cut off. It is better than it cuts the unit off rather than sends it into “pedal to the metal” mode, albeit rather annoying.
As an experiment, it might be worth turning off any phones before you get close to those transmitters just to see if it’s actually your phone talking to the masts which is causing the glitch. Doesn’t help a lot, except proves that Merc electronics are as good as their auto gearboxes.
As for fixing it - probably depends which bit controls cruise control, but if you can find it, then put a copper wire cage (not a closed box) around the device and earth it to the truck which in theory should work…kindof. Oh and do the same around all the cables coming out of said device too. At least it’ll baffle the Merc garage when you take it in for servicing. 
If you want to be really bored:
emcuk.co.uk/awareness/Pages/ … motive.htm
antony-anderson.com/Cruise/7-mech.htm
will look into it ,cheers