Can FTTC adversely affect ADSL speeds?

[#1]

Since August the download speed of my ADSL connection has been in decline.  It used to be consistently around 9500 Mbps but in August it dropped to the low 9000s.  I went away for two weeks in September and when I switched my router back on I could only get in the mid 8000s.  It continued to drop and is now in the range 7500 to 8000.  I have tried two different routers, I have a VDSL filter on the Master Socket fitted about a year ago, I've looked for any indications of REIN coming and going but found nothing.  When I get the chance I will turn-off my power at the mains and let the router run on the UPS to see if that makes a difference but I don't hold out much hope.
What has changed in the last few months is that my area has got FTTC and quite a few people I see have had it installed.  I know crosstalk between wires can cause speed issues for FTTC but can you get enough crosstalk onto ADSL to have an adverse impact on speed there?

[#2]

@ReedRichards
FTTC is based on an entirely different network beyond each cab. With that in mind I suppose the actual physical work to deploy fibre (i.e work being done on the cab) could affect you temporarily if say for example the engineer did something that affected lines other than the one they might be moving on to FTTC.
Beyond that though the fact that there's fibre uptake in the general area shouldn't affect your ADSL speeds at all.