French to English Law/Patents Law: Contract(s) Call to Tender

The following comes from a template included in a Call to Tenders. This page is entitled "Template for Commitment of a Joint & Several Guarantee", and the previous sentence talks about the Bidder declaring that he will make a cash Bid Deposit available in a bank.

This is in Tunisian French

M’engage – nous engageons solidairement, à effectuer le versement du montant garanti susvisé “et dont le soumissionnaire débiteur au titre de……..(inserer l’appel d’offres)……….”, et ce, à la première demande écrite de l’acheteur public sans une mise en demeure ou une quelconque demarche administrative ou juridique préalable.

Here is what I have so far: I/we commit to make payment of the aforementioned guaranteed amount, "and of which the debtor Bidder under the heading......(insert Call to Tender)...., and to do so", on the first written request from the Public Purchaser without any formal notice or any previous administrative or legal steps whatsoever.

What really bothers me is the part in between the quotes, beginning "dont". This should be a clause, but I don't see a verb, and it really doesn't make much sense to me.

Is there something missing, or am I missing something.

Can anyone help?
Thanks