After sending an offer, there are instances where guests are not responding. However, do not take it personally; It may be just that the guest is simply busy or in an environment where it is difficult to connect to the internet.
Give them sometime to consider. In addition, send them a couple messages. In most cases, the guests may have simply missed the notification of a new message.
However, there are also cases where the prices or offers are too expensive for them and are unable to contact them. In this case, you may try and offer them a discount; But always be reasonable not only to the guest but also to yourself. If it does not work out, just let it go. Giving up is also a plausible method. A new guest will come to you eventually.