Paragon Finance and Mortgage Express were the most complained-about home finance providers in H1 2017, according to the Financial Conduct Authority.
The FCA says Paragon had 43.2 complaints per 1,000 home finance balances outstanding.
Former Bradford & Bingley division Mortgage Express had 41.4 complaints per 1,000.
Third was Blemain Finance, with 41.2 complaints per 1,000 balances, followed by Kensington Mortgage Company (39.8) and NRAM (37.4).
Connells was the most complained-about home finance intermediary in H2 2017, with 17.4 grievances per 1,000 sales.
St James Place Wealth Management was second, with 2.2 complaints per 1,000, then Sesame (2).
Investec Bank had the most home finance claims upheld against it in H1 (87.5 per cent).
Legal & General Partnership Services had 80.5 per cent of claims upheld.
It was followed by Coventry Building Society (79.8 per cent), Lloyds Bank (73.3 per cent) and Sainsburys Bank (72.7 per cent).
Black Horse Finance was the most-complained about home finance provider in H2 2016, with 1115 complaints in the period per 1,000 balances outstanding.
The second most-complained about firm was Landmark Mortgages, with 43 FCA grievances per 1,000 balances.
The third was Blemain Finance, with 42.4, then Pepper (UK) with 42 and Shawbrook Bank with 19.9.
Connells was the most complained-about home finance intermediary in the second half of 2016, with 18.1 customer challenges per 1,000 sales.
Following Connells was Sesame, with 2.3 per 1,000 and Firstplus Financial Group with 1.6.