old and new cabinets

can any one help- I have an old cabinet 50 yds from my house which is conected via old u/gound aluminium cable to a telegraph pole 25yds from my house with the telephone, now coming to me at high level.
BT have recently installed a new fibre optic cabinet 60yds from my house. I have for the past 5 years had Talktalk as my providor and used a Netgear router. I recently fell for Talktalk sales pitch of providing new superfast broadband . I said Yes and this was a big mistake -- I told the lad that for years I had problems with the aluminium cable cracking and breaking - he said it would not be a problem and if I did not obtain 40mb I could cancell .
I now find out ,that for me to get some fibre optics - Talk talk ( who subbed it out to BT) simply linked the two cabinets and I am still running on my old aluminium cable.
The results are terrible , much worse than before - I have tried plugging my old netgear router in , but it does not work - Can anyone tell me what I can do ,please

The same would have happened if you swapped to BT as the provider too.

FTTC does not involve a replacement of the final drop wiring to you. What speeds are you managing now, and this is from the master socket and not a data extension and also using Ethernet.

how far apart are the old cabinet and new cabinet?

from what you said it could be 10 yards or 110 yards.

no way the results should be "worse than before" ? What speed ADSL did you have.

Maybe it keeps getting errors and dropping the connection? I imagine VDSL could be more picky than ADSL if there is a bad joint or maybe ADSL ended up with a big target noise margin but VDSL hasn't yet.

Whatever the reason if it really is "worse than ADSL" an engineer callout seems to be needed.