Do you use a telephone answering service?

I would be grateful for recommendations for telephone answering service from the users of this type of service. How much do you pay?

My needs are as follows:

1. To take all my calls and pathes(forward) these to me
2. Does not foward spam calls (ie screens calls)
3. Takes messages when I inform them that I am not available.
4. Needs to be UK based - should speak clearly. No heavy accents that are difficult understand.
5. I do not want to change my number
6. My Calls should not be forwarded to 0845 number

I would appreciate recommendations from users of telephone answering service. It would be good to know the monthly costs for this service.

Thanks