Default wifi BT and NG8

Just upgraded after phone repair , SIM card holder faulty. Wifi reception rubbish, BT crackly, won't let be downgrade to see if it's firmware issue or they've buggered phone when repairing

Samsung S4 on EE 4.2.2 MDM
Xoom US GED 4.0.3

One X on Orange 4.1.1 v3.16.61.6
Sensation 2.3.3 v1.27.161.1
Desire on 2.2
iphone 3gs tried and binned !
Hero - retired