After switching my old supplier wants the advance back — can they?
A final statement (after switching) must be correct within 6 weeks — not "forgotten" advances popping up months later. Here are your rights and the dispute letter.
On switching, the old supplier has 6 weeks to issue a correct final statement, settling advances against actual consumption to switch date. A "forgotten" advance claim arriving after those 6 weeks is in principle invalid: the statutory window has expired and the supplier may only reopen on demonstrable error or fraud. What to do: (1) do NOT pay automatically; (2) request in writing a specified calculation + proof of error; (3) on refusal: formal dispute letter citing the missed deadline (Energy Act); (4) complaint to Geschillencommissie Energie. During dispute the supplier may NOT start debt collection or report to credit bureaus.