They are too big, and it feels like they ultimately don't care. I ordered on the 3rd Nov for a delivery on 17th Nov. This date was missed and after 2 other missed dates, they eventually came on the 25th Nov but wouldn't come into the property as the pipe was "too dirty". Didn't make sense but they were adamant, so I'm 22 days in and no oil. I cancelled and to be fair the customer service team were nice - I didn't appreciate this service charge of £5 which is now £11 and no matter how hard you try, you will not get that back. It feels really galling to pay for a service, which isn't provided only to be £11 out of pocket, how is that right? If you do insist on using them then give yourself plenty of time - assume it won't work and you will need to go local.