Mr Halfon said he recently met constituents who moved into Help to Buy homes built by York-based Persimmon.
He said the houses are shoddy and his constituents view Persimmon as “crooks, cowboys and con artists”.
A Persimmon spokesperson responded: “We have apologised to customers on this development in Harlow, where manufacturing defects with a batch of blocks have created problems with damp. The block manufacturer has agreed that this is the likely root cause of the issue and have offered their sincere apologies.
“We are working hard to rectify the issue as soon as possible and are in contact with the residents on a daily basis.
"Persimmon has agreed to pay the mortgage payments, bills, and the temporary accommodation costs for affected residents while the problem is being addressed.
"We have also been in touch with Robert Halfon again today to arrange a visit to his constituency to meet him alongside the residents in Harlow.”
Persimmon is investing to improve customer satisfaction, after facing a barrage of criticism over build quality. It scored the worst figures of all the major house-builders in the latest Home Builders Federation new homes survey.
In April the firm launched a review of its house quality and customer care functions.
Dave Jenkinson took over as chief executive in February, replacing former chief executive Jeff Fairburn who faced particular criticism after refusing to answer questions over his proposed £110m bonus package. He was eventually awarded £85m over two years.