What you've got are crimps in the block, Your better off having your wires connected via crimps rather than the screw terminals as the old type can be prone to corrosion and/or ants. (found the odd fault obviously caused by an ant who's stood on a couple of terminals in an incommimg call, one fried ant and one HR connection)
The crimps have got a gel in them, if in a soaking wet joint it still takes some time before water can penitrate to the conductors so causing a fault.
I wouldn't recoment using the mains type screw terminal blocks to connect wiring as this can be prone to corrosion in the same way as the screw terminals.
Ok I suppose a peak is ok, but always remember if you fiddle with the wiring and become lost in trying to get it working again, sp's charges for call outs are a bit on the ouch side
If already at a property with out an NTE5 then if feasible then we are supposed to try and fit one. Otherwise if you specificaly ask for one then I don't know what the current situation is but Iwould think this would become a chargeable visit, it's up to your provider so you have to raise the question with them