See if it is on management to waive off notice on payment  then they can ask you serve complete notice period even if you are ready to pay in lieu if no such condition is there send them notice asking resignation acceptance and accept payment in lieu of same.

No, You cannot be forced to work against your wish and can buy notice period if want immediate release. Highest can be happen that you should server notice period, no more extension permitted without employee consent.

You cannot be forced to work against your wishes 

2) complete your notice period and pay salary in lieu of notice period for the shortfall in notice period 

You can file complaint to labour commissioner and he will issue notice to the employer for the same. You will receive your money and relieving letter. 

Your job offer gives you the option to buy out the notice period, either in full or in part. You can't be coerced to serve during the notice period if you are ready to compensate your company.

Hello, 

1. The company cannot compel you to continue in employment after the period of notice you proposed to serve, despite the fact that the notice period is 60 days. 
2. If the alternate option is to pay a month's basic salary, the company should ideally allow you to be relieved. 
3. Mail a simple reminder to the employer about your LWD. 

if the employee wants to leave the company without want to serve the notice period according to the company policy, the employees can pay their equal salary to the company.
other instance, if the company wants to take out the employee with out serve the notice period, the same equal salary company can pay towards the employee.
on your case, if the company can accept to take the one month salary as Lieu account, you are eligible to skip the one month notice period, but if they can claim that replacement training or handover training should be given, you don't have option to wait or escalate to higher level.

1. Since there is a job contract both of you are bound by the terms set therein.

2. As there is clause for notice pay, the company can not make you bound to work for the notice period.

3. So there is nothing to get worried on this account and leave the company when you wish to do so. 

1. You are not bound to work beyond the notice period. Once you serve the notice period you can seek relieving letter from the employer.

2. Having discharged your obligation of serving the notice period, the management cannot ask you to serve till it finds a replacement.

Send by mail your intention to do so if not sent , they can't forced you to work till the replacement comes so give last date of working according to the notice period or intention to buy back the same and leave to join new organization but if you think that the experience certificate and relieving letter of the company is useful for you then don't take harsh action from your side and tell them by mail that as the new employer is pressing hard so I have completed all the work and will leave on such and such date, later on after joining the new company try to persuade for the document or you may say to the new company that to extend you joining period.

Since you have sent only email in this regard and there is no acknowledgment for this yet, you may send a reminder to know about the status of your resignation letter and may intimate that whether or not you may not b working from 01 May anymore and send this communication by registered post or in person and not be email which may not fetch any positing response.

Dont worry about not getting any acknowledgment for this also, this will be an evidence for you to fight it out legally in future if the situation or circumstances warrants one.