Cheap mobile phone calls

We thought we would reduce our phone bill by using a sim card from XLN as most people give their mobile numbers. It costs about £7 a month for 400 calls and has drastically reduced the phone bill in Treats.
I had to buy a cheap phone to use with the sim so I tried Phones 4U but all staff busy and coulnt see anything cheap. Ditto at Carphone Warehouse . So went to T-Mobile and nice girl Azimo gave me a lot of time and help. Phone cost £9.99 but had to buy a £10 top up card for it which she kindly put on my own phone. Job done.
Got back to shop, tried to use phone but it said no sim inserted. Back to T-Mobile. Have to get phone unlocked and they suggested someone. Went there to be told sim not compatible. Dazzle now has new phone!
Try again. Phones 4U ...cheap pay as you go I asked for. Was shown one for £199, excuse me is that cheap? Next offered £175, then £125, £69, £49 and finally £9.99 and salesman said he'd make the sim work. Lost all trust in him by then.
Back to T-Mobile who explained their phones were all locked and should go toCarphone Warehouse. Waited 30mins and just about to leave when salesman became free. Took 5 mins to get sorted. Price of phone? £4.95 and £10 top up ( you have to buy) which we stuck in another phone to use up.
1. T-Mobile good service and helpful
2. Carphone Warehouse short staffed but know their stuff
3. Phones 4U not to trusted
4. XLN for cheap mobile phone calls.
That all took me from about 12 until 3.30 to get sorted. What was so difficult? Shan't be making any calls what's left of today!