Digital Voice upgrade has reduced my internet speeds

[JohnH68]

I have BT Fibre2 broadband and usually have download speeds between 26-27 Mbps. 

Last Friday I had the switch over to Digital Voice by an Openreach Engineer. He also connected us to FTTC. As the cabinet is around 1.2KM from our house the Engineer said that my download speeds should be the same as the cabinet was just outside my local telephone exchange which is 1.2KM from our house so we are still on the existing copper wiring line to this cabinet.

Our download speeds are now reduced to around 20Mbps which is less than the 26Mbps BT guarantee. 

Should my download speed return to previous levels? or is this some kind of fault.

[iniltous]

This doesn’t really make any sense, if you had BT Fibre 2 (which is FTTC , Fibre to the cabinet ) and your speed was 26-27Mb , this is understandable, the speed and product Fibre 2 are associated with FTTC , that  speed wouldn’t be possible from exchange based ADSL , and ADSL doesn’t have Fibre in its product name , so  what do you mean your switch to DV was accompanied by connection to FTTC , if you were already on FTTC 
Perhaps you can provide more details or clarify what you were provided with , FWIW , regular migration to DV doesn’t need an engineer visit unless the customer is classed as vulnerable and then the tech only needs to connect your phone to the router, there is no network intervention needed.

It  would make more sense if you had ADSL and to get DV you were also given FTTC , but in that case you couldn’t have had 26Mb beforehand, especially if you are 1.2 Km from the exchange.

[licquorice]

I'm struggling to understand what exactly the Openreach technician did. Conversion to DV doesn't require a visit, it is a remote operation.

If you were previously getting 26-27Mbps download speed you were already on FTTC so no idea what you mean by "he also connected us to FTTC"

[JohnH68]

I have health issues so, that is why I had a visit from the Openreach Engineer.  He ran a test on the Master socket, went to the local Telephone exchange to switch over DV and came back to see if it was working.   

I didn't realise that I was already on FTTC. The email from Openreach gave me the impression I was moving onto it. Apologies for any confusion. 

So any ideas why my download speed has reduced from 26/27 to 20mbps post DV switch?