"GP refused refer me to another borough's walk in centre"

I am having problem with breathing and within few steps I am getting breathless. So my GP advised me to do ECG within surgery, which was not available for 6 days. So I decided to go to the NHS walk in centre, in Edgware. They require a referral from GP. My GP would not give this referral, as he wanted me to do it only in the surgery and not Edgware Walk In centre, due to it being in a different borough and having cost implications. I couldn't believe it! Now I have complained to the Surgery Practice Manager and Brent - Harrow PCT. I think this surgery should be suspended and the doctor should be punished. The NHS is always shouting about patient choice, but I didn't get it here and I felt that this doctor did not care about me.