I’d ring Ohme, mine wasn’t supplied when the charger was installed, installer said once he’d finished he’d notify Ohme and they’d send it out to me. I rang Ohme to confirm and they said yes, it’s on the way. As it turned out it wasn’t! but another call sorted that out.
Def give them a ring and explain your cable never turned up after the install, and then add “By the way, can I just check it will be the 8m cable as the 5 won’t reach”
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!