If you are unable to collect payment from the customer then you will have the opportunity of asking the guarantor to honour the obligations contained in the guarantee. Obviously an approach has to be made to the guarantor which can be made in the following form; Click here to view sample.
In the event of the guarantor not satisfying the sums due under the guarantee you will then be in a position to consider instituting court action against the guarantor. If you do take court action then this should be instigated against both the customer and the guarantor as the liability will be joint and several.