Had a problem with my BT bill which had gone up unexpectedly so got onto a chat line and ended up with them reducing my bill by a couple of £ a month and doubling my download speed. Obviously pays to complain. 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

Just to wrap this up. My problems continued - slow speed and dropped line. Several more time consuming chats to Vodafone eventually resulted in them sending Openreach to check the line.
But the lines turned out to fine, with no interference or resistance. The Openreach chap went into the village and checked my cabinet connections. He reset my line (DLM profile reset I think) and my speeds bounced back up to 22mbps download but I was told to expect some throttling back over the next few days.

In fact it throttled back quite quickly and also the router was now dropping the line several times a day.
So I bit the bullet and bought a TP-Link Archer VR2800 VDSL router from Amazon with the idea that if there was no improvement I would send it back FOC.
Instance success
I've now got full speed (for my length of line anyway) and no dropped connections since I first turned on.
Very easy to install.
And it also works as a printer server for my old USB laser printer , which is handy.

So the moral is don't waste your time hoping vodafone will come up with an answer just replace their crappy Huawei THG3000G router with a better one.
Vodafone gave me the necessary ID and password without any fuss.
I'm happy now and more importantly so is SWMBO  Jules