Coincidently, my extended EEC family includes several cousins, outlaws and colleagues all living in South West France, and they all report similar "fun" with French postal services and courier firms.
The best solution? Befriend the best local cafe / pâtisserie / wine bar. Be a good regular customer, then ask for a small favour.
Je suis peut-être absent pendant quelques jours. Puis-je recevoir une lettre ici?