FTTC CRC Errors

[#1]

My FTTC has slowed recently and remained doggedly slower, even slowing more. I noticed yesterday that CRC errors Down had all but vanished and were in little more than double figures all day.
Last night, when there is no traffic to speak of (a pair of tablets checking social media whilst we sleep, but both laptop and PC shut down) we had 53000 CRC's.
Does anyone know what this means? Would it suggest a reason for slowing broadband (Up and Down)?

[#2]

Hi Danludlow,
I suggest that you raise a fault as CRC errors are likely to cause poor speeds. It's likely to be an equipment or line fault but it would help if you follow all the checks on the broadband fault checker.
<a href="http://faults.plus.net"> Raise a fault </a>

[#3]

In the last 24 hours, CRC Down errors have dropped to a total 150, a vast improvement, but the speeds have remained doggedly at about 31Mbps Down, and 10 Mbps UP. Its like they are "on rails" when normally speeds vary a bit during the day. Latency is 38-40ms and that high for me, even interleaved, it seems to be creeping upwards over time.
Any thoughts? A non-tecchie gets easily baffled!

[#4]

I've tested the line and their definitely appears to be a line fault. I can see that you have raised this in the past to us but you need to keep rejecting that the fault is clear as we take Openreach's word for it and they told us it was resolved.
The best thing to do is follow the link I've sent above and mention that it's a repeat fault.