Small update I did use a reciprocating saw, the Erbauer erb373 on special offer for 54 quid from screwfix and some bosch wood blades for 13 quid
Managed to cut 2 tree stumps up with it, but it did take 3-4 hours and 3-4 blades up. I simply cut V shape or pizza slices from the side of the stump and removed each slab of wood and repeated till their was just a flat base left then did the same on the top cutting in V shapes. Digging around the stump I was able to get deep down in the roots so left no stumps at all.
70 quid for both the saw and blades, but better then giving someone £300 to cut a single stump !