Making upgardes affordable and quick

There should be an option of intallments or one time payment for anything or only for troops.
The feature will work in the following way :
- When a user wants to upgrade anything there will be option of intallment and of one time payment .
-When user selects one time payent he will have to pay the whole amount of required thing (gold, elixr, dark elixr ) at once and thing will be upgraded instantly.
- When user selects intallment he can pay the amount slowly slowly as he gets the enough amount. But in intallments option upgrade will continue till the user doesn't pays the whole amount.
- He wont get the upgraded thing till he pays the whole amount.
More suggestion

Cost of upgrade can be increased in the intallments option.