Why wait a couple of weeks? Your VM equipment is rented, so you are paying rental for equipment that does not work properly, & for which you get free repairs or replacements if its faulty.
There could be a signal issue (faulty splitter or connector) or it could be the box, but if a fault persists for more than a couple of days then its in your interests to report it via 150 from a VM phone (0345 454 1111 from others).
The Forum Team here can also book engineers, but they may take several days to respond, & then you are looking at 2 - 3 days to a week to get an engineer out.