It will need to be your local MP who takes you case up though, as each MP has to represent their constituents.
Money Saving has received dozens of emails from distraught people whose payments were stopped.
One 28-year-old single mum from Worcestershire who got in touch - she asked not to be named, so we've called her Hannah - was typical of many of the cases we've seen.
She told us she'd resorted to calling Concentrix 67 times in one day after it stopped her tax credits and she was left with no money to feed her two young children.
We also heard from Olivia (whose name we've also changed), a 22-year-old single mum from Liverpool whose payments were suspended without warning when her son was only two weeks old.
Like Hannah, Olivia was accused of living with an "undeclared partner", but unlike her, Olivia says she didn't receive a letter - the money simply stopped one day, and she only found out the reason by phoning Concentrix.
When she called back, she was astounded to learn Concentrix believed a man called "Christoph Pearson" lived with her - a claim she totally denies.
"The only Cristoph I've ever heard of is a character in the Disney film ," she said.
HMRC says those who've had their tax credits stopped will have their cases prioritised and processed as quickly as possible.
Here's what to try, plus stories from those who've had credits stopped, including a single mum whose appeal is still ongoing despite her calling 67 times in one day.
Last week HMRC said it had decided not to extend its contract with Concentrix beyond May 2017 after claims hundreds have had their tax credits unfairly stopped.
Hannah has mild learning difficulties and finds paperwork a struggle.
She used to have a support worker to help her with this type of procedure, but that service was axed due to funding cuts.
That was seven weeks ago and now she, her newborn and her toddler are scraping by on around £44 a week.