Módulo Redsys ha dejado de funcionar  

Buenos días,
el módulo de Redsys ha dejado de funcionar. Al principio no me aparecían ninguna de las formas de pago y desactivando y activando una a una las restricciones de moneda me iban apareciendo hasta que he llegado a la de redsys y entonces la página no carga y me da un "HTTP ERROR 500". La he desactivado y las demás funcionan.
Estoy en la 1.6.1.20
En el error.log me sale esto:
[27-Aug-2018 09:50:58 Europe/Madrid] PHP Warning: Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' (this will throw an Error in a future version of PHP) in /home2/laherbor/public_html/classes/Rijndael.php on line 124
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Warning: Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128' (this will throw an Error in a future version of PHP) in /home2/laherbor/public_html/classes/Rijndael.php on line 124
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Warning: count(): Parameter must be an array or an object that implements Countable in /home2/laherbor/public_html/classes/Cart.php on line 2769
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Warning: count(): Parameter must be an array or an object that implements Countable in /home2/laherbor/public_html/classes/Cart.php on line 2769
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Services_JSON has a deprecated constructor in /home2/laherbor/public_html/modules/redsys/apiRedsys/json.php on line 115
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Services_JSON_Error has a deprecated constructor in /home2/laherbor/public_html/modules/redsys/apiRedsys/json.php on line 781
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Services_JSON_Error has a deprecated constructor in /home2/laherbor/public_html/modules/redsys/apiRedsys/json.php on line 795
[27-Aug-2018 09:51:01 Europe/Madrid] PHP Fatal error: Uncaught Error: Call to undefined function mcrypt_encrypt() in /home2/laherbor/public_html/modules/redsys/apiRedsys/apiRedsysFinal.php:70
Stack trace:
#0 /home2/laherbor/public_html/modules/redsys/apiRedsys/apiRedsysFinal.php(138): RedsysAPI->encrypt_3DES('000000015101', 'xAExB3zxB3rxDCx8E:iLx99x0F]x96x19...')
#1 /home2/laherbor/public_html/modules/redsys/redsys.php(416): RedsysAPI->createMerchantSignature('xAExB3zxB3rxDCx8E:iLx99x0F]x96x19...')
#2 /home2/laherbor/public_html/classes/Hook.php(591): Redsys->hookPayment(Array)
#3 /home2/laherbor/public_html/classes/Hook.php(548): HookCore::coreCallHook(Object(Redsys), 'hookpayment', Array)
#4 /home2/laherbor/public_html/controllers/front/OrderOpcController.php(604): HookCore::exec('displayPayment')
#5 /home2/laherbor/public_html/controllers/front/OrderOpcController.php(541): OrderOpcControllerCore->_getPaymentMethods()
#6 /home2/laherbor/public_html/controllers/front/OrderOpcController.php(421): OrderOpcControllerCore->_assignPayment()
#7 /h in /home2/laherbor/public_html/modules/redsys/apiRedsys/apiRedsysFinal.php on line 70

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