A few short sentences...

[chornik]

Hello guys! I've an English exam in University in a few days and have therefore joined this forum.
I wanted to ask you whether anybody could look over a few sentences for me.

• At this time, it is impossible to say how long the industrial action will endure. (In this case, the part until how long was given and I'm not sure if endure works with how long or whether for how long would be needed)
• In order to apologize for any inconvenience due to the delay in delivery, we will grant you a special discount of 15% on the invoice amount. (Here, I'm not sure whether to say "on the invoice amount" is possible and if "for any inconvenience due to..." works)
• We must ensure that they [new employees] can be made redundant when the demand will sink again.
• The problem is that the trade union will not condone if we will pay out lower wages to the temporary employees than to our regular staff. Therefore we will have to stop offering voluntary fringe benefits.

These would be the first few sentences I've come across while preparing for the first Units of my exam, I hope taking a glance at these is not too much to ask for.

Many thanks,

Chris!