说明你所能做的和不能做的：

We are unable to …

We are able to …

We have been forced to …

环境：

You cannot lower your prices.

We regret that we are unable to reduce out prices.

You have had to raise your prices because the government has increased the sales tax.

We have been forced to raise our prices because the government has increased the sales tax.

However, you can give them a discount of 5% if their order is for more than $8,000.

We are able to give you a discount of 5% if your order is more than $8,000.

With regard to their second question, you cannot accept payment in Egyptian pounds but you can accept US dollars or Euros.

We are sorry that we are unable to accept payments in Egyptian pounds but we are able to accept US dollars or Euros.