Thanks for finding your way to our Forum for help with this, welcome
You haven't stated at which times of day (or night) your connection is experiencing latency. If it's at peak times only then I think that fault ref: F004393400 may be the culprit. A full network upgrade is planned but it may be a while before that work commences, however you should be eligible for a monthly credit in the meantime so I'll pass your details on to another team who'll be in touch in a few days (may be a little longer due to reduced head count over the festive period).
If you find that latency is an issue at off peak times then please set up a Broadband quality monitor and post on here so we can cross reference with our own data.