To echo hottiebottie's post, I'm going to quote at some length from the "Critical Education" blog, as it mentions the legislation underpinning this.
"[Student loans from 2012/13] are not covered by the Consumer Credit Act and interest rates can be set at the discretion of the relevant Secretary of State using secondary instruments, as can the other details of the scheme, such as the repayment threshold (and percentage determining level of repayment). Although the current government has stated its intention to set real rates of interest (ie above inflation) it has given itself powers to set rates much higher than that.
The 2011 Education Act, which received Royal Assent last November, Education Act now allows governments to set up to market rates of interest on student loans using statutory instruments (rates must be ?lower than those prevailing on the market, or no higher than those prevailing on the market, where the other terms on which such loans are provided are more favourable to borrowers than those prevailing on the market.?)
Having recognised this lack of statutory and legal protection, what do the terms and conditions of the student loan agreements say?
The clause that currently appears in the 2012/13 ?STUDENT LOANS ? A GUIDE TO TERMS AND CONDITIONS? allows future administrations great leeway to change terms and conditions.
?You must agree to repay your loan in line with the regulations that apply at the time the repayments are due and as they are amended. The regulations may be replaced by later regulations.? (p. 8)"