Mining-your-tx as a Service?

Question

When I'm sending my transaction, it's "competing" with other transactions for being mined. Are there any mining pools with the following service:

1. I'm giving them my address
2. I'm topping up my balance on their service
3. I'm sending some transaction from my address
4. The pool checks transaction pool and sees the transaction with my address in inputs
5. The pool mines my transaction in the next block (without sorting by priority, comparing fees, etc) and takes some "reward" for it from my balance

Answer 1

I don't see how this would work. If they charge less fees than the current fee they are essentially throwing away money. If they charge more there is no incentive for you to use them. Also you cant expect a mining pool to always include your tx in the next block. If the pool has 30% of the network hashpower you would expect them to mine 1 out of every 3 blocks.