Mosey on down to your local cellphone supplier.  Tell'em you have a european
car and the plug for your fone keeps falling out.  They more than likely
have a box of shims that fit over the plug and generally they'll just give
you one.

Or there is some interesting stuff called magnetic tape.  It has adhesive on
one side.  You can stick some to plastic sides opposite the connector (s)
and it will do fine things keeping those pesky dc plugs in.

Or you could use the now expensive but previously cheap Bosch/John Deere
(silver socket) bits to gin up a better system.

pensioner (fettler in sheeps clothing)