As Sky don't have LLU at the exchange they will not move the customer to ADSL I suspect. To return to the old ADSL supplier means the Sky needs cancelling by Sky and then an order to be placed with a chosen new supplier. Another way may be for a migration to be placed by the chosen ADSL provider, but you need to have ensured that the Ofcom Speed Code of Practice rules on speeds are inforce so that you don't get stung for the 12 month minimum term on the VDSL2.
The cabinet and there is just one for Sorbie is just outside the exchange I believe and 2.1 miles is at the point where if you'd asked anyone on here whether worth ordering there would have been a sharp intake of breath with a line like 'how lucky do you think you are'.
Two postcodes around 2 miles from Sorbie are far enough way I reckon on VDSL2, another in the south east is margin with 3 Mbps, and on the road to Whauphill last postcode on Sorbie exchange has a massive 5 Mbps estimate from us.