Portuguese club Nacional sent the two million euro bill for defender Mexer to a Rennes fans' website rather than the Ligue 1 club.
Ivre, le Nacional de Madère envoie à Stade Rennais Online la facture du transfert de Mexer #TrueStory- Nils Talibart (@nilstalibart) July 12, 2014
Rennes signed Mexer, 26, from Nacional in late June -- but the Madeira club sent the invoice to the wrong place on Saturday.
It went by recorded delivery to the home of Nils Talibart, the webmaster and founder of unofficial fan website Stade Rennais Online.
Talibart, who revealed the exact cost of the Mexer move to be 2.185 million euros, payable in two instalments, told Ouest France he would send the bill to the club after the French bank holiday weekend.