Poor signals in Milton Keynes Area & complaint service

We are family of four and using o2 phone service from long time but struggling with it from last couple of months. We have tried everything in our power to diagnose and resolve the issue without any success. Our nature of jobs demands to have flawless service and 24/7 availability. We are having huge amount of drop calls i.e calls dropping during the conversation, phones not ringing at all and getting missed call message, can't make call, failed call message on dialling. Our children are using o2 number too and walking from school to home everyday . They find it very difficult to call if they need it.

So far we have done following measures to resolve it.

- contacted Apple Store to find out if phone have issue, they have confirmed that There is no issue with phone and all four phone can't have issue at same time
- changed one of the phone and bought new s6 Samsung but situation with o2 signals stayed same poor one bar or no service inside home.
- from last 3 days talking to o2 customer service /engineers to diagnose the issue, they disconnected phone , reconnected after 48 hours. Situation remains same.
- tried using ee and all the phones works brilliantly. no issue at all.
- phones are unlocked to all the networks, it seems the issue resides with o2.
- try using tugo but it have own issues. It may be good to make call but hard to pickup calls.

We can't take this any more. O2 is really going down with regard to service and whole process where you cant talk to anyone except few call logger customer agents. O2 should not offer services to any such area where they cant offer their services properly. Sent complaint
complaintreviewservice
and received automatic reply that they will contact in 7 days.