If you want to complain to a person you don’t well, be careful! A direct complaint or criticism can sound very rude or aggressive.
It may be best to mention the problem more indirectly by saying:
I’m sorry to have say that but…
I’m sorry to bother you but…
I think you may have forgotten…
It may have slipped you mind, but…
There may have been a misunderstanding about…
In some situation, but only if you’re talking to someone you know really well, it may be necessary to say more directly:
What are you going to do about…?
I’m not at satisfied with…
But only in extreme cases, if you’ve already tried more polite methods, would you have to threaten someone:
Look, if you don’t send your engineer to repair the machine, we will be forced /obliged to cancel our next order.
Or you can write:
Unless you pay the account within seven days, we will please the matter in the hands of our solicitors/ attorneys…
If someone complains to you, or if you think they’re likely to complain, it may be wise to apologize-even if it wasn’t really your fault. Then you can promise to put things right:
Sorry, my fault.
I’m very sorry. I didn’t realize.
There has been a slip-up/problem in our…dept.
Or you can write:
We are very sorry about the delay/mistake…
We wish to apologize for…
Please accept our apologies for…
It may be best to mention the problem more indirectly by saying:
I’m sorry to have say that but…
I’m sorry to bother you but…
I think you may have forgotten…
It may have slipped you mind, but…
There may have been a misunderstanding about…
In some situation, but only if you’re talking to someone you know really well, it may be necessary to say more directly:
What are you going to do about…?
I’m not at satisfied with…
But only in extreme cases, if you’ve already tried more polite methods, would you have to threaten someone:
Look, if you don’t send your engineer to repair the machine, we will be forced /obliged to cancel our next order.
Or you can write:
Unless you pay the account within seven days, we will please the matter in the hands of our solicitors/ attorneys…
If someone complains to you, or if you think they’re likely to complain, it may be wise to apologize-even if it wasn’t really your fault. Then you can promise to put things right:
Sorry, my fault.
I’m very sorry. I didn’t realize.
There has been a slip-up/problem in our…dept.
Or you can write:
We are very sorry about the delay/mistake…
We wish to apologize for…
Please accept our apologies for…