Unable To Install Apps - Error code: D000F001 - Windows Phone 7

I bought a Nokia with Windows Phone 7.8 a few months ago. Everything was fine but since today I can't install ANY APPLICATION from Marketplace. 

I've hard reset phone and added to a new Microsoft Account. Practical, I have a hole new identity and Phone it's recovered from factory settings. 

Why I can't still install applications ?

I bought a Nokia with Windows Phone 7.8 a few months ago. Everything was fine but since today I can't install ANY APPLICATION from Marketplace. 

I've hard reset phone and added to a new Microsoft Account. Practical, I have a hole new identity and Phone it's recovered from factory settings. 

Why I can't still install applications ?

I have 2 Lumia 800's which have just been a great phone but I have been forced to buy a cheap Android phone due to this development.

My main Lumia lost the ability to receive Gmail and on advice from a phone tech expert I reset it to factory settings and that pretty much bricked it. It still works as a phone but all the Apps I had are gone and can't be reloaded because of this support change. I wouldn't be worried if there was some way of installing apps without going through the Marketplace but I can't find one. My spare Lumia is still working but only has the Nokia drive app installed but after buying a $29 pre-paid android phone I will probably just bin it as they are now worthless.

So if you have an early Windows phone that is still working do not reset it or it will be a brick.

If that is the case then it simply despicable. What then do we do with the phones we have in our possession?

HTC 7 Mozart T8698

7706.WM7_Main(mojobld).20110706-1450

Firmware: 2250.21.40401.206

Region:English (United Kingdom)

Language:English

Speech: Play audio confirmations is on and Read incoming text messages aloud is set at Bluetooth only

Sever name: m.hotmail.com

Cameroon

MTN Cameroon