The following is based on the information provided in your post.
We take the downstream ES (Errored Seconds), which is 9653 and divide it by the uptime (16 days, 19 hours and 21 minutes) in hours (which in this case is 403.35 hours). 9653 / 403.35 gives a figure of 23.93206892277179, or 24 if rounded to the nearest whole number. The figure of 24 is how many ES per hour. If we divide the 60 (which represents an hour) by 24 (the amount of ES per hour) then we can see that there is an ES every 2.5 minutes (or 150 seconds if multiply 2.5 by 60).
The calculated Mean Team Between Errors (MTBE) is 150 (over the space of your uptime). Which means, because you are on Plusnet (who use Speed DLM profile), your line would be classified as Amber (i.e. no changes from the DLM).
You can find out more about the DLM here:
http://www.kitz.co.uk/adsl/DLM.htmCould you get more speed out of your line? Yes, potentially, seeing as the modem supports G.INP. G.INP will not give you a speed boost in itself, and I do not know the exact prerequisites for G.INP to be enabled, but if it is able to reduce the errors experienced through impulses of errors to get your MTBE above 300 (as the Green threshold for the Speed profile), then we could see the SNR reduced to as low as 3 dB thus giving you a boost.
Is there a scope for improvements in your speed currently? No. Be that the short answer.
Of course, there may be slight discrepancies in my post since I do not know if the FRITZ!Box retains error information after any downtime.
Edited to fix error in post.