Mercedes says it can’t find a vital part for my 2018 car

Without a repair, the indicators and headlights on the Mercedes E 350 won’t work. Photograph: Alamy

I own a Mercedes E 350, bought new in 2018. Six months ago, it needed a new control unit for the headlamps and indicator, but this has been impossible to source, and the dealer tells me there is no supply and my complaint to Mercedes-Benz UK yielded no response. The MOT for my car is due this month and, without headlamps or indicator, it will fail.
ME, Evenley, Northamptonshire

In March, another reader feared their 2018 Jeep might have to be written off because, according to Fiat, the part could not be found anywhere in the world and would take a year to produce. Remarkably, Fiat conjured up the apparently nonexistent item when I questioned it. And, wondrously, your dealer called to report that the unit had arrived the week I contacted Mercedes-Benz UK.