Are these senteces correct?

[JRD]

We have been facing repeated complaints from the project side for the transport service which needs to be provided by you on request without any delay. This point was clearly mentioned in the agreement when the contract was made.
As you know, you are not providing the transport service upon our request and always the delivery was delayed without any genuine reasons. This will not be acceptable to us. So, we have decided to closure of our business with your company.

[Tdol]

I'd change:

for the transport service which needs to be provided by you on request without any delay...

about the transport service which you should provide without delay on request
The next bit is unclear- you talk of an agreement and a contract. Are they two different things? If not, then say ...on request, as agreed in the contract. or as agreed.

The transport service has not been provided promptly and deliveries are always (always or frequently??) delayed without any satisfactory explanation.

The last bit depends on what sort of agreement you had with them.

[Tdol]

I'd change:

for the transport service which needs to be provided by you on request without any delay...

about the transport service which you should provide without delay on request
The next bit is unclear- you talk of an agreement and a contract. Are they two different things? If not, then say ...on request, as agreed in the contract. or as agreed.

The transport service has not been provided promptly and deliveries are always (always or frequently??) delayed without any satisfactory explanation.

The last bit depends on what sort of agreement you had with them.

[bhaisahab]

We have been facing repeated complaints from the project side about the transport service, which should be provided by you on request without any delay. This point was clearly mentioned in the agreement when the contract was made.
As you know, you are not providing the transport service upon our request and always the delivery was delayed without any genuine reasons. This is not acceptable to us. So, we have decided to terminate our business with your company.

I have made a few alterations, I think that it is ok now.