If you abscond, or leave on bad terms, then your HR department may get stroppy and refuse to give you a copy of the withdrawal notification form, or refuse to sign it, or delay passing it through to the fund administrator. But your former employer is bound by the fund rules to submit the completed claim forms to the fund administrator. 

If they do not do so, they are in breach of the fund rules. It is the duty of the Fund trustees to ensure that the Fund complies with the rules, so you need to inform the Trustees that your former employer is not signing and submitting the claim form. To this end, you should therefore send a registered letter to the Fund Trustees (typically care of the fund administrator) informing them that the employer is preventing you from claiming your fund. You may want to send a copy of the letter to your former employer (Head of HR, Head of Finance etc) by way of e-mail, so they are aware that you have taken this step. 

Failing this step, you can then report the matter to the Pension funds Adjudicator. Only the following deductions are permitted from your provident fund: 

 (a) any amount which is payable by you to the employer or the Fund at the date of your retirement or discharge, or which the employer is liable to pay in respect of you. (b) any amount which has been paid to you, to which you are not entitled. (c) the amount of any loss which has been sustained by the employer through theft, fraud, negligence or any misconduct on your part and which has been admitted by such member or pensioner in writing or has been proved in a court of law; (d) any amount, plus interest at the rate determined by the Board after consultation with the actuary, due to the Fund in respect of an amount for which the Fund becomes liable under a guarantee furnished in respect of a loan granted to you by some other person to that member in terms of the rules. These amounts may be deducted from your benefit in a lump sum or in such installments as the Board may determine. Your employer may put a hold on your payment for a few months, pending a court case to resolve amounts in dispute.