As you have only just had VDSL installed, it will still be in its training period. This means that you will likely see many resyncs as DLM works out the best place for your line. The increased SNRM implies that it has intervened to deal with a high error rate, probably with interleaving + RS error correction.
On a line with no faults, this shouldn't really have happened, so I would suggest that you try to get your hands on a DSLStats compatible modem or modem/router such as a HG612, or a ZyXEL VMG series (1312, and 8X24 series are good choices). This will allow us to see detailed information about your connection and work out if there is any cause for concern.
The training period is 10 days to my knowledge, so if you are still concerned it may be worth ringing BT and asking them to perform a GEA test to detect any faults from their end. Be careful though, as some faults, such as a rectified loop, are more often than not internal wiring issues, and if an engineer comes out and discovers this, there is a hefty fee, sometime up to £200.
Another thing you could do is go to this site and enter your phone number:
https://www.btwholesale.com/includes/adsl/adsl.htm?s_cid=ws_furls_adslcheckerThis will allow you to find out which cabinet you are on, and your estimated speeds. You can then enter your phone number on this website:
https://www.telecom-tariffs.co.uk/codelook.htmThis site will return a result showing your exchange. If you click on this, then click on 'List all x fibre cabinets', then find your cabinet in the list to show an approximate location and brand. The brand is the important thing in this case, as it will indicate whether or not you have access to a technology called G.Inp, which can be used as an alternative to interleaving + RS error correction on more stable lines.
On another note, what is your current ping? A high ping can indicate the use of interleaving on a line, so a ping higher than around 20ms can sometime be an indicator.
