Asalamualikum Mufti sahib
May Allah reward you for your efforts.
I have recently bought a townhome from an existing home owner. The house was built in 2012 and new appliances were installed at that time.
about 2 months after I moved in, there seems to be some problem with the appliances. Occasionally, the microwave plate keeps spinning and the timer counts down without actually heating the food and the refrigerator has to put on the max thermostat value to keep things cold. The milk was spoiled a couple of times. Both of them work most of the times.
I called the appliance manufacture to check if they are still under warranty. I was told that the appliances were out of warranty but was offered an opportunity to renew them for a fee. she informed me that the appliances must be under working conditions. They said I could make the service call only after 1 month after subscription
When I mentioned to them about the existing conditions, I was offered a warranty on a higher price. I declined and called again after a few days.
Another sales rep was informed about the existing condition and she readily offered the warranties on the lower prices.
I already took the warranties but have an option to cancel them
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The warranty explained in the query is impermissible, as it constitutes Gharar (uncertainty).
In principle, any transaction in which the return for one’s payment is uncertain due to being suspended on an uncertain event is impermissible. 
In the inquired case, the return of the payment towards the warranty is unknown, as it is uncertain whether the product will be required to be replaced/repaired or not. In the case it does require a replacement or repair, the extent of the requirement is unknown, for example whether the replacement or repair will be required only once or more times.
Hence, such a transaction is not permissible.
And Allah Ta’āla Knows Best
(Mufti) Abdul Azeem bin Abdur Rahman
Checked and Approved by my Esteemed Teachers,
Hadhrat Mufti Emraan Vawda Saheb (Damat Barakatuhum)
Hadhrat Mufti Husain Kadodia Saheb (Damat Barakatuhum)
The Shar’a ruling herein given is based specifically on the question posed and should be read in conjunction with the question.
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 وحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَبْدُ اللهِ بْنُ إِدْرِيسَ، وَيَحْيَى بْنُ سَعِيدٍ، وَأَبُو أُسَامَةَ، عَنْ عُبَيْدِ اللهِ، ح وحَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، وَاللَّفْظُ لَهُ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ عُبَيْدِ اللهِ، حَدَّثَنِي أَبُو الزِّنَادِ، عَنِ الْأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ: «نَهَى رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ عَنْ بَيْعِ الْحَصَاةِ، وَعَنْ بَيْعِ الْغَرَرِ (صحيح مسلم)
لِأَنَّ الْقِمَارَ مِنْ الْقَمَرِ الَّذِي يَزْدَادُ تَارَةً وَيَنْقُصُ أُخْرَى، وَسُمِّيَ الْقِمَارُ قِمَارًا لِأَنَّ كُلَّ وَاحِدٍ مِنْ الْمُقَامِرَيْنِ مِمَّنْ يَجُوزُ أَنْ يَذْهَبَ مَالُهُ إلَى صَاحِبِهِ، وَيَجُوزُ أَنْ يَسْتَفِيدَ مَالَ صَاحِبِهِ وَهُوَ حَرَامٌ بِالنَّصِّ، وَلَا كَذَلِكَ إذَا شُرِطَ مِنْ جَانِبٍ وَاحِدٍ لِأَنَّ الزِّيَادَةَ وَالنُّقْصَانَ لَا تُمْكِنُ فِيهِمَا بَلْ فِي أَحَدِهِمَا تُمْكِنُ الزِّيَادَةُ (رد المحتار، ج 6، ص 403، سعيد)