Hi, I know this thread is a few months old now but I've just had a very similar problem returning my old kit. My old v6 box stopped working in mid June (just the power supply but VM replaced the whole lot and deactivated it so I lost all my series links). I was sent a replacement V6 box along with a second V6 box to replace an old Tivo box that I had apparently been paying £10 a month for the last few years but never used (I was told at the time that I could use it for free). I asked to return the Tivo box and the 2nd V6 box (which looked like someone had tried to it open it with a screwdriver and arrived with no remote, cables or returns label) .
I received a return box for the Tivo unit that was too small to fit it in and no return label for the 2nd V6 box . After an age going round the houses with whatsapp chat etc an appointment was made for VM to collect the kit on July 10th, I waited in all day but no one came to collect (I've been receiving texts every day for weeks saying I hadn't returned the kit). VM Whatsapp chat only got me as far as being sent 3 new returns boxes, I managed to actually speak to a real person this morning who told me to just through the old kit away! Why doesn't VM tell you this straight away instead of warning that if you don't return the kit you will be charged for it?
I was also told in mid June that I needed an engineer visit to sort out some fault that I didn't know I had, I waited in for the visit but no one came, when I rang VM I was told that they had cancelled the visit without telling me so I had wasted an afternoon waiting.