português para inglês Adm./Finanças Seguros customer satisfaction survey from a gas supplier

Hi everyone,

I was wondering if anyone could help me with this phrase as I'm not sure I'm understanding it correctly.

It comes from a customer satisfaction survey for a gas supplier from Brazil and is to be translated into UK English.

The question asked was:
"Finally, do you have any additional comments to make regarding your experience with {company}?"

The full answer given was:

"Em setembro de 2016, ganhamos um desconto só que por algum motivo o boleto foi trocado com o desconto, mais foi gerado nova nota fiscal, então a outra nota sem o desconto ficou em aberto quando fomos ligar para solicitar um nada consta de 2016, houve muito transtorno, mais conseguimos"

My translation so far is as follows but I am not at all confident with it:

"In September 2016, we got a discount, yet, for some reason, the bank slip was swapped with the discount. Another invoice was produced, then the other invoice without the discount remained open. When we called to ask about it, there was nothing from 2016. There was a lot of disruption but we got there."

Many thanks for your help.

Kind regards,

Kerryann