Tense to use with "would"

The present tense is sometimes used in English to express the future, and that is what is required here. Paying the bank’s charges and receiving the full amount have yet to happen. To express this, the sentence needs to end with ‘to ensure that we receive the full amount.’

I see a distinct variation in meaning:
"... to ensure that we received the full amount" implies that the amount is already received 'at the time of the instruction'.
Whereas,
"... to ensure that we receive the full amount" implies that the amount would eventually be received (precluding any possibility of future default).

In fact, the overall sentence is prone to ambiguity because of too many clauses combined.

The use of the past tense here (received) is an example of deferential backshift. As the rest of the sentence makes clear, the speaker is going out of his or her way not to cause offense. This kind of deferential backshift is common in requests such as:

"I was wondering if you could help me."

Or:

"Excuse me, I wanted to see the headmaster. Is he free?"