(1) It would give us great pleasure to render you a similar service should an opportunity occur.

(2) We wish to reciprocate the goodwill.

(3) We shall on a similar occasion be pleased to reciprocate.

(4) We hope to be able to reciprocate your good offices on a similar occasion.

(5) We are always ready to render you such of similar services.

(6) We shall at all times be willing to reciprocate such of similar favour.

(7) We shall be happy to have an opportunity of reciprocating to you on a similar occasion.