ING Direct will boost the number of staff employed in credit assessment after service times on broker-originated mortgage refinancings blew out to several weeks.More than thirty credit assessors worked over the weekend to clear a backlog of mortgage applications caused by a surge in demand and residual headaches stemming from the bank's new broker platform.ING Direct's head of third party distribution Mark Woolnough told Banking Day that service times on applications from borrowers buying new properties had improved to five days following the "weekend blitz", but this was still well short of the company's target of two-day turnarounds on approvals."We've made a decision to prioritise loan applications from people purchasing properties ahead of refinancings," he said."As of Monday we have reduced the waiting time on purchase applications to five days from seven."However, brokers will have to wait longer to get applications for mortgage refinancings approved.In a memo sent to brokers last week, ING revealed that the backlog meant it was taking more than two weeks to process refinancings.According to disclosures on the bank's broker platform on Monday (17 July), credit assessors yesterday were still processing refinance applications received on 3 July.Woolnough described the delays as "unacceptable" and promised that the bank was taking steps to fix the problem."We're looking at hiring ten new credit assessors in the next month," he said.Woolnough said the delays were also partly due to the introduction of a loan origination system developed by banking software company, Sandstone Technology.While most of the glitches associated with bedding down of the system were ironed out earlier this year, Woolnough indicated that the bank was still dealing with its impact on processing backlogs."We should have been a little more open and transparent about the issues we've been having," he said."We have had some implementation challenges around the platform we delivered to market last year."The straight-through processing platform is similar to the one developed by Sandstone for Bendigo and Adelaide Bank's third party business.Adelaide Bank began rolling out the new system, known as LendFast, earlier this month to brokers across the country.ING Direct sources around 90 per cent of its mortgage business through brokers.