Article use

'Treatment' is uncountable there. Here is a sentence where the word is countable:

She received three long treatments from her podiatrist last week, but her feet still hurt.

Mister Micawber'Treatment' is uncountable there. Here is a sentence where the word is countable:She received three long treatments from her podiatrist last week, but her feet still hurt.

Thanks a lot teacher. That was helpful.

Also, why is it wrong to use 'by a customer' instead of 'from a customer' in the original sentence?

Usage of 'from': (Active voice sentences.)
We got a complaint from a customer.
We got a bad review from a customer.
We got bad treatment from a customer.

Usage of 'by': (Passive voice sentences.)
The complaint letter was written by a customer.
We were insulted by a customer.
We were beaten by a competitor.

AlpheccaStarsUsage of 'from': (Active voice sentences.)We got a complaint from a customer.We got a bad review from a customer.We got bad treatment from a customer.Usage of 'by': (Passive voice sentences.)The complaint letter was written by a customer. We were insulted by a customer.We were beaten by a competitor.

Got it, that is very helpful. Thanks a lot.

AnonymousI understand that 'encountered' works the same as 'got' in your examples. Am I right?

Yes.

AlpheccaStarsYes.

Thanks a lot, again!